Abstraction géométrique is an interactive installation made of a video projector, a trackball and a computer with special software.Abstraction Géométrique allows visitors to navigate through the representation of a wide public place divided in two parts, thus two images: outside and inside.With help of a trackball, the user moves in the image: left, right, up, down, but also zoom in and out.The images, two views inside and outside the plaza of La Defense (business district in Paris, France), are altered in some places by white geometric areas, erased. These scrubs were performed on any trademark, logo, advertising... noticeable in the image.